Method and apparatus for removing organic waste from water

ABSTRACT

A method for removing contaminants from water involves filtering the water through a filtering apparatus which includes a porous media container having an inner chamber which is suitably configured so that water can pass through the chamber and processed straw retained within and suitably within the chamber such that when water passes through the chamber, it also passes through the straw. A method is provided for enhancing the composting ( 470 ) of organic matter, e.g., sludge, including the steps of adding processed straw to a compost mixture and digesting said mixture.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to methods and devices for usingprocessed straw to remove organic waste (ammonium, nitrites, nitrates,and hydrogen sulfide), from water, effluent and sludge.

2. Description of the Prior Art

Effective disposal of and recycling of organic waste can posesignificant challenges. There are many techniques for removal of organicwaste from water or for recycling of this waste into fertilizer.Similarly, the removal of organic waste through known processes canyield a useful fertilizer and substrate for plant growth. Theavailability of processed straw, manufactured according to U.S. Pat. No.4,924,808 issued May 15, 1990, which is incorporated herein byreference, encouraged its evaluation in a broad range of applicationsbeyond its original intended use as a cat litter.

Organic waste in water, particularly nitrogenous waste, is undesirableand must be removed before the water can be drained into waterways.Increased nutrients are known to harm the ecosystem into which thecontaminated waters flow. Furthermore, organic waste, particularlynitrogenous waste, can accumulate in sources of water used in drinkingor in agricultural applications as well as in closed aquatic systems,such as aquaria and closed fish and aquaculture systems.

Human and animal waste, including waste from food processing plants andeffluent from aquaculture operations are sources of water-solublenitrate-nitrogen which accumulates to dangerous levels in groundwater,drinking water, ponds, lakes, rivers and estuaries. Consequences of thisbuild-up include poor water quality and the stimulation of unwanted andoften dangerous growths of algae, which require nitrate as an essentialnutrient. One example is the accumulation of nitrate in aquaria,resulting in algae blooms. A whole industry has been spawned, producingchemicals and devices for algae growth prevention, for removal ofnitrogenous compounds, and for testing for levels of these compounds.

In aquaculture environments, nitrogenous waste (ammonia, nitrites andnitrates) result from the metabolic process of creatures living in agiven body of water and from decay of organic matter in the water. Agreat deal of organic waste can accumulate in a confined body of watersuch as an aquarium or fishery, due to the unnatural overcrowding ofanimal life in these settings. Accumulation of organic waste is harmfulto animal and plant life within these closed aquatic environments. Whileammonia and nitrite accumulation can be particularly devastating,resulting in the rapid demise of the inhabitants of the aquarium orfishery, accumulation of nitrates is also harmful to these inhabitants.Removal of nitrogenous waste from water, including nitrates, istherefore desirable.

Contaminated water, whether in an aquarium or a fishery, or in amunicipal waste facility, is generally treated similarly to convertnitrogenous waste to nitrates. Water or sludge containing nitrogenousmatter, is contacted with a substrate having certain microorganismdeposited thereon, where it is aerobically converted to ammonia,nitrite, and later to nitrate. The substrate is often contained within atrickle filter. The microorganisms are of the types best adapted to thenutritional and physical conditions of the treatment system and includecertain aerobic chemoheterotrophic bacteria and fungi which often ariseby selection from the microorganisms initially present in the waste. Forinstance, degradation of organic waste and/or animal metabolism oftenresults in production of ammonia, which is aerobically converted tonitrite and then to nitrate by Nitrosomonas and Nitrobacter species,respectively. The process of conversion of ammonia to nitrate is knownas nitrification.

Removal of nitrates after decay and treatment of organic matter in watercan be achieved in a number of ways. In waste water treatment, thenitrate-containing water either can be discharged, or further treated toremove nitrates, often by assimilation into plant matter. In an aquariumenvironment, nitrates can be removed by a number of methods. Thesimplest method for reducing nitrates is through water changes or byassimilation into plant matter. Assimilated ammonia, nitrites andnitrates, as well as phosphates and other contaminants are removed fromthe enclosed aquatic system by continuous harvesting of the plantmatter. Growth of and harvesting of plant matter is often effective,provided the plants and/or algae can be efficiently grown. For manyreasons, efficient plant and/or algal growth may be unattainable orundesirable in certain systems as they may clog filtration and pipingsystems. In marine environments, protein skimming can aid in maintaininglower nutrient levels by removal of organic waste before it can bedegraded to ammonia, nitrite and nitrate. Combined with low levels ofdenitrification (conversion of nitrate to N2) that can occur in anoxicareas of the aquatic system, nitrates can often be effectivelycontrolled. However, achieving very low levels of nitrates through thismethod is often difficult or impossible to achieve, especially when fishare kept in the aquatic system.

A number of unique methods have been developed to combat accumulation ofnitrates in an aquatic system which involve passing a quantity of waterinto a portion of a filter system where anoxic conditions are present,wherein denitrifying organisms grown. These systems can be difficult,expensive and/or complicated to maintain. There is also a risk thatanaerobic production of hydrogen sulfide can result. Therefore there isa need for a simple, inexpensive and safe method for reducing nitratelevels in aquaria, aquaculture and waste water treatment systems and ofhydrogen sulfide as well.

Sewage sludge is a by-product created in sewage plants during wastewater treatment. A similar sludge results from agricultural waste oranimal waste and effluent produced by the animal industry (cattle,especially dairy cattle, pigs, horses, intensively housed sheep andgoats, poultry, and aquaculture). Treated, rotted, and partiallysolidified effluent and sludge is mostly spread on agricultural fieldsas a fertilizer and growth substrate. The benefits for the agriculturalindustry are that the nutrients in the effluent/sludge provide variousnitrogen compounds, phosphate and potassium salts, which are importantfor plant growth. Favorable times for the application of sewage sludgeare between Fall and Spring since most fields are easily accessible atthis time, prior to cropping. However, little to no plant growth at thistime makes this impractical because the nutrient use and absorption bythe plants range from very little to none. In addition, large amounts ofprecipitation can wash out nutrients and allow the nitrogen compounds topenetrate into groundwater resources. The elution of water solublenitrogen compounds is one of the greatest threats to ground and drinkingwater.

Nitrogen in sewage sludge consists mostly of ammonium-nitrogen (NH4—N).Ammonium-nitrogen is a common compound found in anaerobically rottedsludge. After sludge application, ammonium-nitrogen is converted intonitrate-nitrogen (NO3) within only a few days, making it water solubleand, thus, available to the groundwater. Drinking water has strictlimits for both nitrate and ammonium.

It is therefore an object of the present invention to provide a simple,inexpensive and safe method for removal of nitrogenous waste (ammonia,nitrite and nitrate) from water and a filter apparatus for directremoval of nitrogenous waste from water.

It is a further object of this present invention to provide and improvean organic fertilizer having reduced levels of elutable nitrogencompounds, to provide a method for imparting sustained nitrogen releasequalities to composted organic material, i.e., effluent/sludge, for useas fertilizer and to provide a method to increase the rate of productionof fertilizer from compost.

SUMMARY OF THE INVENTION

A water filtering apparatus is provided, including a porous mediacontainer having an inner chamber and suitable configured so that watercan pass through the chamber, and processed straw retaining within andsuitably configured within the chamber such that when water passesthrough the chamber, it also passes through the straw.

A method for removing organic material from water is provided, includingfiltering water through a filtering apparatus which includes a porousmedia container having an inner chamber which is suitable configured sothat water can pass through the chamber, and processed straw retainedwithin and suitably within the chamber such that when water passesthrough the chamber, it also passes through the straw.

A method is provided for enhancing the composting of organic matter,including the steps of adding processed straw to a compost mixture anddigesting said mixture.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a manufacturing flow chart of the method for production ofprocessed straw according to the present invention;

FIG. 2 is a partially broken-away perspective view of a filter bagaccording to a first embodiment of the present invention;

FIG. 3 is a partially broken-away perspective view of a filter pouchaccording to a second embodiment of the present invention;

FIG. 4 is a partially broken-away perspective view of a canister filteraccording to the third embodiment of the present invention; and

FIG. 5 is a schematic diagram of a sewage sludge treatment systemaccording to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Processed straw is effective for removal of organic waste, especiallynitrogenous waste, from water for improving compost based fertilizers.

Processed straw is prepared in a number of fashions. One method formanufacturing processed straw is the method of U.S. Pat. No. 4,924,808,wherein straw is dried to a moisture content of between 8% to 14% byweight, chopped, compacted into briquettes and, the, crushed intogranules.

FIG. 1 shows an alternative method for preparing processed straw. Strawis dried to a moisture content of 8% to 14% and is then shredded andmilled. The shredded and milled straw is screened for size. The largersized fraction is useful in water filters. The fine straw particleswhich pass through the screen may be used or further processed for otherpurposes, such as for cat litter, according to U.S. Pat. No. 4,924,808.In the screening step, the minimum size of the retained processed strawis determined with regard to the ultimate use of the processed straw.For instance, in a water filter, the chosen size of the particles ofprocessed straw depends upon a number of factors, such as, the choice ofthe media container and filtration device in which the straw isretained. Choice of particle size may further be determined by optimallybalancing the surface area of the processed straw particles, the desiredflow rates through the media container within the filter and/or desiredrate of removal of waste. A higher surface area of the processed strawwould result in a slower water flow rate, but would increase thewaste-removal rate of the straw. If a filter system is used which forcespressurized water through a filter element, smaller particle sizes canbe used. In any case, the processed straw particles should be largerthan the openings/pores of the container in which the straw is retained.

For certain applications, shredded and milled straw, weather screened orunscreened, is further processed by compressing the processed straw intopellets and either milling or crumbling the pellets. This processedstraw can be either packaged for use or screened for size, once again,according to the ultimate use of the processed straw.

Water Purification

In water, nitrogenous waste (ammonium, nitrite and nitrates) is presenteither in solution, as gas, or as solids. Filtering water throughprocessed straw prevents the undesirable and/or dangerous build-up ofnitrogen compounds in bodies of water, whether stagnant (ponds, lagoons,lakes without exit, fish tanks), flowing (river or raceways—eithernatural or artificial—or closed fish production systems with movingwaters), and in moving waters in coastal and ocean rim areas (estuaries,lagoons, bays, inlets and fjords). Build-up of waste materials in thesebodies can be a result of natural processes or from pollution.Filtration with processed straw also decreases the concentration ofodors from nitrogenous compounds. Nitrogen binding by processed strawis, therefore, for the purpose of, removal of nitrogen compounds fromwater, prevention of nitrogen compounds from entering drinking water,inhibition, prevention or reduction of undesirable algae growth,production of improved fertilizer from human and animal waste, and fromfood processing waste, and decreasing the concentration of odors fromnitrogenous compounds.

Processed straw can be used successfully to reduce nitrate levels inwater over a period of days through a process not yet fully understood,but is effective in the prevention of unwanted and undesirable growth ofalgae.

The following examples show how processed straw achieved over time areduction of nitrogenous compounds and adversely affected the growth ofalgae in closed aquatic systems.

EXAMPLE 1

Pouches containing 5 g of processed straw were used. In the first study5 pouches were added to 1000 L of salt-water in a glass container(aquarium). The nitrate concentration went from 125 ppm to <100 ppm in48 hours <50 ppm in 50 hours <25 ppm in 96 hours and <10 ppm in 120hours.

EXAMPLE 2

In a second study, 2 pouches containing 5 g of processed straw have beenused in three different tanks holding 460 L of fresh-water each. Nitritelevels in Tank 1 have been determined at 10 ppm, tank 2 with 20 ppm, andtank 3 with 20 ppm. After 4 days the nitrite levels had fallen to 0.1ppm in tank 1, 2.5 ppm in tank 2, and 0.1 ppm in tank 3.

EXAMPLE 3

In this study, using the same test, algae growth was tested in only 6 Lof water, using 0.8 g of processed straw. Algae growth was reduced by44% within 8 days.

EXAMPLE 4

In a field trial, a 55 L fresh-water aquarium stocked with seahorses andstarfish and heavily contaminated with hair algae was treated with onepouch containing 8 g of processed straw each week for four weeks. Thenitrate concentration in the water was determined using a commercialtest kit and a content of 40 ppm was shown just before treatment. Within8 days the nitrate concentrations had fallen to 0 ppm and remained atthis level. Algae disappeared over the four week period.

EXAMPLE 5

In a field trial, a 380 L salt-water aquarium contaminated with greenand brown algae was treated with a pouch containing 8 g of processedstraw. The nitrate levels dropped from 40 ppm to 0 ppm within 3 days andremained at that level at the end of the observation period of 8 weeks.Algae disappeared after 3 weeks.

EXAMPLE 6

In a field trial, a 180 L fresh-water aquarium was treated with a pouchcontaining 6 g of processed straw, reducing nitrate levels from 40 ppmto 0 ppm within 3 days.

These results clearly indicate a significant reduction of nitrogenouscompounds at all degrees of salinity, and, consequently, a sharpreduction in the growth of algae, as a side effect, resulting fromtreating contaminated water with processed straw. Significant resultsmay be seen already within three to four days after treatment commenced.Preferably, the amount of straw is 0.002% to 1.25% by weight of thetotal volume of water to be filtered in a closed system, such as, in anaquarium or closed aquaculture facility. The total volume of water to befiltered is equal to the volume of water contained in the closed aquaticsystem, including, but not limited to, water in sumps, filters, proteinskimmers and tubes or pipes.

The type of filtering device or apparatus in which the processed strawis used is a matter of choice. The filtering apparatus includes a porousmedia container having an inner chamber and configured to allow passageof water through the chamber. Processed straw is retained within thechamber and is suitable configured therein so that water which passesthrough the chamber also passes through the processed straw. Forinstance, suitable media containers include, without limitation,pouches, including fabric or mesh pouches and plastic cages or boxes.Processed straw can be used in canister filters, hang-on filters, insumps or placed directly into the body of water to be filtered.

FIG. 2 is a cut-away elevational view of a first embodiment of thepresent invention. A typical commercially available mesh filter bag 100is packed with processed straw 120. The filter bag 100 may be inserteddirectly into a body of water to be treated, or it can be inserted intoa suitable filter apparatus, including, without limitation, canisterfilters, hang-on-tank filters, sumps and sump filters or in-line with awater pump. Like numbers in FIGS. 3 and 4, refer to like elements inFIG. 2.

FIG. 3 is a cut-away perspective view of a second embodiment of thepresent invention. A filter pouch 200 is provided. The filter pouch 200is formed from a mesh pocket 210 and has a seal 215 in this embodiment.Processed straw is retained within the mesh pocket 210. The filter pouch200 can be suitably sized and shaped to fit commercially availablefilters and filter chambers. The seal 215 is optional, depending uponthe configuration of the filter pouch 200 and the material used from themesh pocket 210.

FIG. 4 is a cut-away elevational view of a third embodiment of thepresent invention. A canister filter 300 is provided. The canisterfilter 300 includes a housing 310, a water inlet 312 and a water outlet314. The housing 310 is suitably configured to allow water which issiphoned, pumped or otherwise taken from a body of water (not shown) topass from the inlet 312, through any media 316 within the canisterfilter 300 and to the outlet 314 for return to the body of water. Themedia 316 includes processed straw 320. The filter bag 100, the filterpouch 200 and the canister filter 300 are, without limitation, separate,but equivalent, embodiments of the media container of the presentinvention.

FIG. 5 shows a flow diagram of a typical integrated sewage sludgetreatment system and illustrates a method for processing sludge,utilizing the methods of the present invention with regard to processingsludge to produce a fertilizer. The sludge treatment system 400 includesa sludge inlet 410; a collection tank 420 in which sludge is collectedand a rotting tower 430 in which the sludge is anaerobically fermentedor digested in the presence of processed straw.

Anaerobically digested sludge is sent from the rotting tower 430 tomixing tanks 440 wherein the water content of the rotted sludge isreduced to about 70% for better incineration and/or composing. Dryingthe rotted sludge decreases operating expenses in a sludge treatmentsystem. Water is further removed trough press systems such as a beltfilter, screw press, frame press etc. 450 and the dried, rotted sludgeis either incinerated in an incinerator 460, producing further energyand/or composted in a composter 470 with processed straw, for use asfertilizer. Water extracted in this system and according to this methodcan be filtered through processed straw according to the presentinvention to remove waste therein.

Effluent/Sludge Treatment

The following are typical results from studies and field trialsconfirming this invention's purpose with regard to reduction of watersoluble nitrogen from sludge during treatment of human and animal waste,including waste from the food processing industry, by adding processedstraw.

Effluent/sewage sludge is a by-product created in sewage plants duringwaste water treatment. Sludge also results from agricultural waste oranimal waste produced in the animal industry (cattle, especially dairycattle, pigs, horses, intensively housed sheep and goats, poultry, andaquaculture). Hence the term “sludge” used in this inventionencompasses, without limitation, waste of plants human and/or animalorigin, and the by-products from the food processing industry, such asdairy facilities, cheese factories, rendering plants, abattoirs,facilities for the canning and processing of fruit and vegetables, farmsand the like.

This invention describes the beneficial effects realized from theaddition of processed straw to sludge, when followed by a briefanaerobic rotting or aerobic composting method. Namely, addition ofprocessed straw reduces the content of elutable nitrogen compounds, thuspreventing loss of nutrients, as well as groundwater contamination. Forthis procedure processed straw is added to wet effluent/sludge.Preferably the mixture of sludge and processed straw is 0.1% to 10% byweight, processed straw. The sludge mixture is composted, or rotted,resulting in a superior fertilizer with reduced quantities of elutablenitrogen compounds. Any form of processed straw may be used.

During the intensive rotting process, all easily degraded substances,mainly from the sludge, are eliminated. An increase of rotting bacteriaoccurs at the same rate as the degradation. This growth in bacterialpopulation requires nutrients which the bacteria also extract from thesewage sludge. Water soluble nitrogen compounds such as ammonium andnitrate are required by the microorganisms in order to produce bacterialprotein mass. Nutrients absorbed by the microorganisms are incorporatedinto proteins are protected from elution.

Since the nitrogen compounds in sludge prepared according to the presentinvention are contained in microbial protein, continuous degradationallows for a slow and gradual release of the nutrients after theprocessed sludge is applied as fertilizer to the land. Depending on soiltemperature and soil moisture level, the microorganisms die off overseveral weeks and the organically bound nitrogen therein is againmineralized, making these nutrients available during times of increasedplant growth.

For instance, during normal springtime growth, plants can absorb theslowly released nitrogenous compounds without elution of nitrogenouscompounds into the soil or groundwater.

EXAMPLE 1

In one study, pure sludge was found to contain 56 mg per liter ofsoluble, extractable nitrogen in the form of ammonium-nitrogen. Themixture of sludge and processed straw, prior to composting contained 73mg/l of ammonium-nitrogen. After 14 days of processing, the sludge andstraw mixture showed a content of only 3 mg/l of extractableammonium-nitrogen. None of the three samples studied showed any nitrateconcentrations. Thus, adding processed straw reduced the solublenitrogen (washout nitrogen) from 73.8 mg/l to 3 mg/l, a reduction of96%. It is important to note that the nitrogen had not been lost throughthe process but rather had been absorbed into the biomass of themicroorganisms of the processed straw, protecting it from elution.

EXAMPLE 2

In a second study, a laboratory scale procedure was utilized for theanalysis. Each unit was comprised of a 5 L glass sealed vesselcontaining approximately 2 L swine manure with a dry solid contend of2%. All analytical procedures were in accordance to EPA and ASTMmethods.

A 0.5% addition of processed straw has shown to decrease ammoniavolatilization from the slurry by approximately 20% for up to 1 day postaddition. Atmospheric hydrogen sulfide release, was also shown to beinhibited.

EXAMPLE 3

A large scale study, using 55 Gallon containers filled with swine manurefrom a breeding facility, showed a reduction of nitrogen ammonia by 66%and a reduction of hydrogen sulfide by 32% during the early phase ofrotting, using a 0.5% addition of processed straw.

The objects of the invention have been met. A simple, inexpensive andsafe method and apparatus for removing nitrogenous compounds from wateris described herein. Processed straw is inexpensive and easy to use andis shown effectively to remove nitrogenous waste compounds from waterunder safe aerobic conditions. Furthermore, a fertilizer and a methodfor production thereof from sludge is provided resulting in a fertilizerwhich is rapidly produced from sludge and having sustained nitrogenrelease capabilities.

Lastly, an integrated system is provided, utilizing all facets of thepresent invention with improvement in the effectiveness of and theeconomy of sludge reclamation as compared to such systems known in theart.

The above invention has been described with reference to the preferredembodiment. Obvious modifications and alterations will occur to othersupon reading and understanding the preceding detailed description. It isintended that the invention be construed as including all suchmodifications and alterations.

What is claimed is:
 1. A method of reducing water soluble nitrogen inwater in a closed aquatic system comprising: processing straw by drying,shredding, and milling it; screening the milled straw; enclosing largerfractions of the processed straw within one or more water penetrablecontainers formed from a material selected from the group consisting offabric, metal, synthetic solid, and fiber, and adding the containerbound straw to the water in the closed aquatic system in a weight ratioof straw to water of 0.002% to 1.25%.
 2. The method of claim 1, whereinthe straw is dried to a moisture content of 8% to 14%.
 3. The method ofclaim 1, wherein the straw is further processed by compacting it intobriquettes, then crushing it into granules.
 4. The method of claim 1,wherein the closed aquatic system is selected from the group consistingof an aquarium, a fishery, and a pond.
 5. The method of claim 1, whereinthe container of straw is added directly to the water.
 6. The method ofclaim 1, wherein the container is selected from the group consisting ofa mesh pouch, a canister filter, and a hang-on filter.
 7. A method ofreducing water soluble nitrogen in water in a closed aquatic systemcomprising: processing straw by drying, shredding, and milling it;enclosing the processed straw within one or more containers; andfiltering the water in the closed aquatic system through the straw. 8.The method of claim 7, wherein the container is placed in-line with awater pump to filter the water through the straw.
 9. The method of claim7, wherein the straw is placed in a canister filter having a water inletand a water outlet thereon.
 10. The method of claim 7, wherein thecontainer is a mesh pouch made of fabric.